JPH05159268A - Magnetic recording medium and its production thereof - Google Patents

Abstract

PURPOSE:To decrease noises and to improve C/N by providing a 1st magnetic layer essentially consisting of Co and Cr or Co, Ni and Cr by inclining an axis of easy magnetization. CONSTITUTION:The 1st magnetic layer 2 essentially consisting of the Co and Cr is provided directly or via a substrate layer on a high-polymer substrate 1. The direction inclined with a normal direction 5 is set as the axis of easy magnetization and the angle formed by the direction 4 where columnar crystal grains are grown and the normal direction 5 is set smaller than the angle formed by the direction 3 of the axis of easy magnetization and the normal direction 5. The behavior of magnetic walls is thereby made adequate and the noises are decreased. C/N is the improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium used in a high density recording / reproducing apparatus such as a digital VTR and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, magnetic recording / reproducing devices have tended to become smaller and have higher densities, and in the magnetic recording medium (hereinafter simply referred to as "medium") used therein, there is a limit to the densification of conventional coating type media. A metal thin film type medium has been attracting attention as a material to overcome. In this regard, a metal thin film type medium made of Co-Ni-O has been put to practical use as a magnetic tape for VTR. In order to form such a magnetic recording medium with high productivity, for example, a web coater type continuous vapor deposition apparatus using a cylindrical roller system is used to move a long polymer substrate and form a magnetic layer on it. It may be vapor-deposited continuously.
At this time, the oblique deposition method is used to improve the high density recording / reproducing characteristics as compared with the conventional coating type medium due to the contribution of the magnetization component in the direction perpendicular to the film surface of the magnetic layer.

However, a medium compatible with a next-generation VTR such as a home digital VTR and a high-definition VTR is required to have further excellent high-density recording / reproducing characteristics, and Co-Cr and Co-Ni-Cr are candidates for the medium. , C
A perpendicular magnetic recording medium containing o-O, Co-Ni-O or the like as a main component is expected.

In these perpendicular magnetic recording media, the reproduction output in the long wavelength recording region is low in recording and reproduction using a ring type magnetic head, and the isolated reproduction waveform has a dipulse shape, which makes it difficult to perform digital signal processing. There was a problem. These problems are caused by a method such that the easy axis of magnetization is inclined with respect to the normal line of the substrate by the oblique vapor deposition method to take in the contribution of an appropriate in-plane magnetization component, or a laminated structure is adopted. A method has been proposed for solving it without impairing the density characteristics. Also, Co and Cr or C
The medium containing the magnetic layer containing o, Ni and Cr as the main components is a next-generation VTR due to energetic research and development in various fields.
As a compatible magnetic tape, extremely superior performance has been obtained overall, and it is expected that the performance will be further improved in the future.

[0005]

However, there are some points in which this comprehensively excellent medium is inferior to the conventional medium in terms of individual performance. For example, the noise tends to be higher than that of the metal thin film type medium containing Co-Ni-O as the main component, and if the noise can be reduced while maintaining the current output, the C / N ratio can be further increased. There is room for improvement.

It is an object of the present invention to provide a magnetic recording medium having an improved C / N ratio by reducing noise and a method for manufacturing the magnetic recording medium.

[0007]

To achieve this object, the present invention provides a non-magnetic substrate and Co and Cr or C formed on the non-magnetic substrate directly or through an underlayer.
a magnetic film containing a first magnetic layer containing o, Ni and Cr as main components, and a direction in which an easy axis of magnetization of the first magnetic layer is inclined with respect to a normal direction of the non-magnetic substrate. In the magnetic recording medium, the angle formed by the growth direction of the columnar crystal grains forming the first magnetic layer and the normal direction is smaller than the angle formed by the easy axis of magnetization and the normal direction. It is a thing.

[0008]

With this structure, the growth direction is different from the easy magnetization axis direction, and the growth direction is close to the normal direction, so that the behavior of the domain wall changes, noise is reduced, and the C / N ratio is improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a medium according to an embodiment of the present invention. In FIG. 1, 1 is a polymer substrate, 2 is a first magnetic layer mainly composed of Co and Cr formed on the polymer substrate 1, 3 is an easy magnetization axis direction of the first magnetic layer 2, Reference numeral 4 is the growth direction of the columnar crystal grains forming the first magnetic layer 2, and 5 is the normal direction of the polymer substrate 1. Also, θ
₁ represents an angle formed by the growth direction 4 and the normal direction 5, and θ ₂ represents an angle formed by the easy magnetization axis direction 3 and the normal direction 5.

In the magnetic recording medium in which the first magnetic layer 2 containing Co and Cr as the main components is formed on the polymer substrate 1, in order to tilt the easy magnetization axis direction 3 with respect to the normal direction 5, When a method such as an oblique vapor deposition method is used, columnar crystal grains generally grow in a direction inclined with respect to the normal direction 5.

As an example of a conventional medium, the angle formed between the growth direction of columnar crystal grains of the magnetic layer containing Co and Cr or Co, Ni and Cr as the main components and the normal direction of the non-magnetic substrate is the magnetization. The angle was equal to or greater than the angle formed by the easy axis direction and the normal direction. However, when the magnetic layer is formed by a web coater-type continuous vapor deposition device using a cylindrical roller system as described above, the columnar crystal grains are not linearly grown but are slightly curved. Then, the tangential direction of the curved line at the center point in the film thickness direction of the magnetic layer is defined as the growth direction of the columnar crystal grains.

However, Co and Cr or C
In the magnetic layer containing o, Ni and Cr as the main components, it is the hexagonal close-packed structure (h) of Co that mainly contributes to the magnetic anisotropy.
cp), and it is considered that the contribution of shape anisotropy due to the growth direction of columnar crystal grains is extremely small. Therefore, if the c-axis of Co is tilted in an appropriate direction with respect to the normal direction, no matter what direction the columnar crystal grains are tilted with respect to the normal direction, the ring-type magnetic head can be used for recording and reproduction. It is believed that a magnetic layer having an easy axis of magnetization inclined in a suitable direction can be obtained.

From this point of view, Co and Cr are mainly used.
Method of growing columnar crystal grains in the first magnetic layer 2 as a component
Angle θ between direction 4 and normal 5₁And easy magnetization axis direction 3
Angle θ with line direction 5₂Where we examined the relationship between
R, as shown in FIG.₁Is θ ₂Configuration much smaller than
In a medium having
We have found that noise can be reduced. Note that FIG.
Is the relative movement between the magnetic head and the medium during recording and reproduction.
FIG. 3 is a cross-sectional view of the medium viewed from a plane parallel to the moving direction. Sanawa
In the medium of FIG. 1, the c axis of Co is almost the easy axis of magnetization.
Although growing in the direction 3, the columnar crystal grains are in the easy magnetization axis direction.
It grows in a direction rather close to the normal direction 5 than 3.

In such a medium, a sufficient study result has not yet been obtained on the mechanism for reducing noise, but since the individual columnar crystal grains are magnetically separated by the segregation of Cr, the It is considered that the behavior of the domain wall changes if the growth direction 4 is changed with respect to the normal direction 5. As a result, the columnar crystal grains are moved in the normal direction 5
It is thought that a mechanism such that the head-on domain is less likely to occur is caused when the growth is performed in the direction close to

According to the vacuum evaporation method, the first magnetic layer 2 having Co and Cr as the main components, which has the above-mentioned structure, has an incident angle of vaporized atoms to the polymer substrate 1 of 50 with respect to the normal direction 5.
After forming the lower layer 2a at an angle of at least 50 °, the incident angle of the vaporized atoms on the polymer substrate 1 is 45 ° with respect to the normal direction 5 on the lower layer
The following is obtained by forming the upper layer 2b and making the layer thickness of the lower layer 2a 20% or less of the layer thickness of the entire first magnetic layer 2.

This mechanism is considered as follows. The formation of the lower layer 2a determines the growth direction of the c-axis of Co. That is, the c-axis of the upper layer 2b formed on this layer inherits the growth direction of the c-axis of the lower layer 2a and grows in a direction inclined with respect to the normal direction 5 with respect to the incident direction of the vaporized atoms to the polymer substrate 1. To do. On the other hand, the columnar crystal grains grow in a direction closer to the normal direction 5 than the growth direction of the c-axis, that is, the direction according to the incident angle of the vaporized atoms to the polymer substrate 1. In this way, the angle θ ₁ formed by the columnar crystal grain growth direction 4 and the normal direction 5 is sufficiently smaller than the angle θ ₂ formed by the easy magnetization axis direction 3 and the normal direction 5. Magnetic layer 2 is obtained.

In the above manufacturing method, the role of the lower layer 2a is to determine the growth direction of the c-axis, that is, the direction 3 of the easy axis of magnetization. Therefore, the layer thickness can be made sufficiently smaller than that of the upper layer 2b. On the contrary, if the layer thickness of the lower layer 2a is larger than necessary, the contribution from the lower layer 2a to noise becomes large, or the growth direction of the columnar crystal grains of the upper layer 2b is affected, and the value of θ ₁ approaches θ ₂ . There are also adverse effects such as. From this point of view, the thickness of the lower layer 2a is preferably 20% or less of the total magnetic layer thickness. Further, when the incident angle of the vaporized atoms to the polymer substrate 1 when forming the lower layer 2a is smaller than 50 ° with respect to the normal direction 5, the function of determining the growth direction of the c-axis is reduced, and the c-axis of the upper layer 2b is reduced. Is not preferable because it may grow in a direction close to the growth direction of columnar crystal grains. In addition, θ ₁ becomes θ ₂
In order to obtain a sufficient noise reduction effect by making the size smaller than that, it is preferable that the incident angle of the vaporized atoms on the polymer substrate 1 when forming the upper layer 2b is 45 ° or less with respect to the normal direction 5.

FIG. 1 shows an example in which the first magnetic layer 2 contains Co and Cr as main components.
Those containing Ni and Cr as main components, or those containing impurities added thereto may be used. Further, FIG. 1 shows an example in which the polymer substrate 1 is used for the purpose of application to a magnetic tape for VTR and the like, but the above noise reduction effect can be obtained even if another non-magnetic substrate 1 is used. Of course.

Further, when an underlayer is interposed between the first magnetic layer 2 and the non-magnetic substrate 1, or, for example, a Co--O film or C
Containing components other than the first magnetic layer 2 containing Co and Cr or Co, Ni and Cr as a main component, such as a medium having a laminated structure with another second magnetic layer such as an o-Ni-O film. Even in the case of doing so, the effect can be obtained.

Next, a method of manufacturing the medium in one embodiment of the present invention will be described. FIG. 2 shows a web coater type continuous vapor deposition apparatus using a cylindrical roller system as an example of a magnetic recording medium manufacturing apparatus of the present invention. In this figure, 1 is a long polymer substrate, and 7 and 8 are a supply roll and a winding roll of the polymer substrate 1, respectively. The polymer substrate 1 has an arrow A on the circumferential surface of the cylindrical roller 9.
The vaporized atoms are accumulated while traveling in the direction of. At this time, a shield 11 is provided between the evaporation source 10 and the cylindrical roller 9 to appropriately control the incident angle of the vaporized atoms to the polymer substrate 1, so that the easy axis of magnetization is in the normal direction of the polymer substrate 1. A tilted medium is formed.

In the medium shown in FIG. 1, the shield 11
Thus, although the lower layer and the upper layer are continuously formed in the same vacuum container, the forming process of the lower layer and the upper layer may be separately performed twice. In FIG. 2, the evaporation source 10 is Co and Cr or Co, Ni and Cr.
Although two separate evaporation sources 10 for forming the lower layer and the upper layer are provided as the alloy of No. 1, but if there is no problem in terms of the layer thickness ratio of the lower layer and the upper layer, the film forming rate, etc., one evaporation source is used. The source 10 may form both layers. Further, the vapor deposition sources 10 for Co, Ni, and Cr, which are the constituent elements of the first magnetic layer, may be separately provided to perform multi-source vapor deposition. In FIG. 2, in the lower layer, the incident angle of vaporized atoms to the polymer substrate 1 is between the initial incident angle φ ₁ and the final incident angle φ ₂ , and in the upper layer, between the initial incident angle φ ₃ and the final incident angle φ ₄ . It is formed by. Therefore, according to the manufacturing method of the present invention, the shield 11 may be set so as to satisfy the conditions of φ ₁ > φ ₂ ≧ 50 ° and 45 ° ≧ φ ₃ > φ ₄ .

Hereinafter, the medium of the present invention manufactured by using the continuous vapor deposition apparatus shown in FIG. 2 will be specifically described with reference to preferred examples and comparative examples.

(Embodiment 1) The evaporation source 10 is composed of Co and Cr.
As a alloy, form a Co-Cr film on the heat-resistant polymer substrate 1.
I made it. The incident angle of vaporized atoms is φ with respect to the normal direction.₁=
65 °, φ₂= 50 °, φ₃= 30 °, φ_Four= 10 °
The thickness of the lower layer, which is responsible for determining the direction of the easy axis of magnetization, is 30 nm,
The thickness of the upper layer is 220 nm, so the total thickness of the first magnetic layer is
Was 250 nm. The magnetism of the medium produced under the above conditions
Angle θ formed by the axial direction and the normal direction ₂Is the torque measurement
According to the report, it was 45 °. In addition, a transmission electron microscope (T
The cross section of the medium in the transport direction of the polymer substrate 1 is viewed by EM).
As a result, it was confirmed that the growth direction of the columnar crystal grains and the normal direction were not
Angle θ₁Was confirmed to be 15 °. Note that θ₁Is
According to the above definition, the total thickness of the first magnetic layer is 250 nm.
The tangential direction of the curved line of the columnar grain at the center point
It is an angle with the line direction.

(Comparative Example 1) The shield 11 of the continuous vapor deposition apparatus used for preparing the medium of Example 1 was changed, and the incident angle of vaporized atoms to the polymer substrate 1 was changed from the initial incident angle of 60 ° to the final incident angle of 25 °. A Co-Cr film was formed between the two. The thickness of the first magnetic layer was 250 nm, which is the same as the total thickness of the first magnetic layers of Example 1. The film forming speed, the degree of vacuum in the container, the saturation magnetization of the first magnetic layer, and other conditions were all the same as in Example 1. Θ ₂ of the medium manufactured under the above conditions is 45 °, θ ₁
Was 50 °. That is, in Example 1, the C of a single layer was formed without forming the lower layer responsible for determining the direction of the easy axis of magnetization.
Since the o-Cr film is formed, the growth direction of the columnar crystal grains substantially coincides with the easy axis of magnetization, and the medium structure of the present invention is not provided.

The medium obtained in Example 1 and Comparative Example 1 was slit into a magnetic tape medium, and a single frequency recording / reproduction was performed using a VTR deck. The relative moving speed between the magnetic tape and the magnetic head at this time was set to 3.8 m / s. The obtained noise spectrum is shown in FIG. The reproducing capacities of the magnetic tape media of Example 1 and Comparative Example 1 are almost the same in the measured recording frequency region, and the noise comparison shown in FIG. 3 can directly correspond to the C / N ratio comparison. In Example 1, remarkable noise reduction was achieved in all measurement wavelength regions, and the effect of the present invention was clarified. Co-Cr
When some impurities are added to the film, and when Co--Ni--
When a Cr film or a film obtained by adding a slight amount of impurities to the Cr film was also examined, the same results as above were obtained.

(Embodiment 2) Next, on the first magnetic layer containing Co and Cr or Co, Ni and Cr as the main components, Co and O or the second component containing Co, Ni and O as the main components. The effects of the present invention in a medium having a magnetic layer formed thereon will be described. FIG. 4 shows the same Co—Cr second magnetic layer 2 on the polymer substrate 1 as in FIG.
3 is a structural example of the medium of the present invention in which the magnetic layer 12 is sequentially formed to form the magnetic film 13, and is a cross-sectional view of the medium in the relative movement direction of the magnetic head and the medium during recording and reproduction. After forming the first magnetic layer 2 on the heat-resistant polymer substrate 1 by using the continuous vapor deposition apparatus shown in FIG. 2, the second magnetic layer 12 is formed by the continuous vapor deposition method, and the medium shown in FIG. It was made.

First, when the first magnetic layer 2 is formed, the incident angle of vaporized atoms to the polymer substrate 1 is φ ₁ = 8 with respect to the normal direction.
0 °, φ ₂ = 60 °, φ ₃ = 35 °, φ ₄ = 10 °, and the thickness of the lower layer responsible for determining the easy axis direction 3 is 15 nm,
The thickness of the upper layer was 85 nm, and thus the total thickness of the first magnetic layer 2 was 100 nm. The angle θ ₂ formed by the easy magnetization axis 3 of the first magnetic layer 2 formed under the above conditions and the normal direction 5 is 6
It was 0 °. It was also confirmed that the angle θ ₁ formed by the growth direction 4 of the columnar crystal grains and the normal direction 5 was 20 °. Next, the production of the second magnetic layer 12 made of Co—O
Of the continuous vapor deposition apparatus used for producing the magnetic layer 2 of
Is changed to set the incident angle of the vaporized atoms to the polymer substrate 1 between the initial incident angle of 60 ° and the final incident angle of 20 °, and oxygen is introduced into the vicinity of the Co-filled evaporation source to perform reactive vapor deposition. It was The layer thickness of the second magnetic layer 12 was 150 nm, and thus the total magnetic layer thickness including the first magnetic layer 2 was 250 nm. The angle θ ₃ formed by the easy-axis direction 14 of the second magnetic layer 12 and the normal direction 5 was 50 °. This value is obtained by measuring the torque of the second magnetic layer 12 directly formed on the polymer substrate 1 without the first magnetic layer 2.

A medium comprising a magnetic film 13 in which a second magnetic layer 12 having a direction 14 of easy axis of magnetization in a direction inclined with respect to the normal direction 5 is formed on the first magnetic layer 2 is currently used. Co-Cr, Co-Ni-Cr, and Co that have received attention
Among the metal thin film type media containing —O, Co—Ni—O, etc. as the main components, it has particularly excellent recording / reproducing characteristics from the low density recording area to the high density recording area. In the medium of Example 2, the first magnetic layer 2 has particularly excellent recording / reproducing characteristics. In the medium of Example 2, by increasing θ ₂ of the first magnetic layer 2 to increase the contribution of the in-plane magnetization component, a high reproduction output in a low recording density region can be secured and a high reproduction output can be obtained. It is considered that this is due to the realization of the attribution magnetization mode in which the recording / reproducing efficiency is obtained.

From this viewpoint, the value of θ ₂ is determined by the second magnetic layer 1
It is necessary to make it larger than the angle θ ₃ formed by the direction 14 of the easy axis of magnetization 2 and the normal direction 5. Further, in order to realize the recording magnetization mode in which high recording and reproducing efficiency as described above is obtained,
As shown in the explanatory view of the magnetic recording method of FIG. 5, the direction 15 of the relative movement of the magnetic head with respect to the medium is such that the direction of the head magnetic field 17 near the leading edge 16 is substantially the same as the direction 14 of the easy magnetization axis of the second magnetic layer 12. It is preferable to set in the direction. In FIG. 5, 18 is a head gap and 19 is a trailing edge.

(Embodiment 2) The shield 11 of the continuous vapor deposition apparatus used for manufacturing the medium of Embodiment 2 is changed so that the incident angle of vaporized atoms to the polymer substrate is from the initial incident angle of 80 ° to the final incident angle of 3.
A first magnetic layer made of Co—Cr was formed between 0 °, and then a second magnetic layer made of Co—O was formed by a continuous vapor deposition method. The layer thickness of the first magnetic layer was 100 nm, which is the same as the total thickness of the first magnetic layer of Example 2. The first
The conditions other than the above, such as the film forming rate at the time of manufacturing the magnetic layer, the degree of vacuum in the container, the saturation magnetization of the first magnetic layer, etc., are all the same as in Example 2. Θ of the first magnetic layer produced under the above conditions
₂ was 60 ° and θ ₁ was 60 °. That is, Comparative Example 1
Similarly to the above, the growth direction of the columnar crystal grains substantially coincides with the easy axis of magnetization, and the medium structure of the present invention is not provided.
The second magnetic layer was manufactured under the same conditions as in Example 2.

(Embodiment 3) The shield 11 of the continuous vapor deposition apparatus used for producing the medium of Embodiment 2 was changed so that the incident angle of vaporized atoms to the polymer substrate was from the initial incident angle of 35 ° to the final incident angle of 1.
A first magnetic layer made of Co—Cr was formed between 0 °, and then a second magnetic layer made of Co—O was formed by a continuous vapor deposition method. The thickness of the first magnetic layer was 100 nm, which is the same as the total thickness of the first magnetic layer of Example 2. The conditions other than the above, such as the film forming rate during the production of the first magnetic layer, the degree of vacuum in the container, and the saturation magnetization of the first magnetic layer, are the same as those in the second embodiment. The first magnetic layer produced under the above conditions had a θ ₂ of 10 ° and a θ ₁ of 15 °. The second magnetic layer was manufactured under the same conditions as in Example 2. That is, Comparative Example 3
In the second magnetic layer, the growth direction of the columnar crystal grains substantially coincides with the easy axis of magnetization, and θ ₂ is significantly smaller than θ ₃ of the second magnetic layer. It is not a medium structure.

(Comparative Example 4) Co on a heat-resistant polymer substrate
A medium having a single magnetic layer of —O was prepared. Co-
The O single layer was manufactured by changing the shield 11 of the continuous vapor deposition apparatus used for manufacturing the first magnetic layer made of Co—Cr in Example 2 to change the incident angle of vaporized atoms to the substrate to an initial incident angle of 60 °. The final incident angle was set to 20 °, and oxygen was introduced into the vicinity of the Co-filled evaporation source to carry out reactive vapor deposition. Co
The layer thickness of the -O single layer is 250 n, which is the same as the total magnetic layer thickness of Example 2.
m. The conditions other than the above, such as the film forming rate at the time of producing the Co—O single layer, the degree of vacuum in the container, and the saturation magnetization of the magnetic layer, are the same as those at the time of producing the second magnetic layer of the second embodiment. The angle θ ₃ formed between the easy axis of magnetization and the normal direction of the manufactured Co—O single layer was 50 °.

The media obtained in Example 2 and Comparative Examples 2 to 4 were slit into magnetic tape media, and VTR
Single-frequency recording / playback was performed using the deck. At this time, the relative moving speed between the magnetic tape and the magnetic head is 3.8 m.
/ S. The recording density characteristics of the obtained reproduction output and noise are shown in FIGS.

In the second embodiment, high output characteristics and low noise characteristics are realized in all measured recording frequency regions. Comparative Example 2 has the same high output as that of Example 2, but the first magnetic layer 1 has θ ₁ as large as θ ₂ and does not have the constitution of the present invention. The noise is significantly higher than that of 2.

[0035] Comparative Example 3, since the theta ₁ of the first magnetic layer is less than equal to Example 2, the noise is similarly low values Example 2 is realized. However, since the value of θ ₂ is as small as θ ₁ , the contribution of the in-plane magnetization component in the first magnetic layer is small, and the reproduction output is remarkably low especially in the low recording density region. In the medium having the structure of Comparative Example 3, the reproduction output in the low recording density region can be compensated to some extent by increasing the film thickness or the saturation magnetization of the first magnetic layer. In this case, noise increases as the film thickness or the saturation magnetization increases, so that the C / N ratio eventually becomes worse than that in the second embodiment. Further, increasing the thickness of the magnetic layer to about 300 nm or more is not practical from the viewpoint of running property in the VTR deck and tribology in sliding with the magnetic head.

In Comparative Example 4, the lowest noise among the four media shown in FIG. 6 was realized.
Since there is no contribution of the in-plane magnetization component of the first magnetic layer made of Cr, the reproduction output is lower than in Comparative Example 3.

The case where a slight amount of impurities was added to Co--Cr as the first magnetic layer, and the case where Co--Ni--Cr or a film obtained by adding a small amount of impurities thereto was used instead of Co--Cr was used. As a result of studying also, the same result as above was obtained. Further, as the second magnetic layer, Co
When the case of adding a small amount of impurities to —O and the case of adding Co—Ni—O or a small amount of impurities in place of Co—O were also examined, the same results as above were also obtained. That is, in a medium in which a second magnetic layer containing Co and / or Co, Ni and O as main components is formed on a first magnetic layer containing Co and Cr or Co, Ni and Cr as main components, The effect of the invention was recognized.

[0038]

As is apparent from the above description, the magnetic recording medium of the present invention has a structure in which the easy axis of magnetization is inclined and contains the first magnetic layer containing Co and Cr or Co, Ni and Cr as the main components. As a result, the C / N ratio is improved by reducing the noise.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a magnetic recording medium manufacturing apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of noise recording density characteristics.

FIG. 4 is a schematic sectional view of a magnetic recording medium according to a second embodiment of the invention.

FIG. 5 is a diagram illustrating a recording method on the magnetic recording medium.

FIG. 6A is a diagram showing an example of a recording density characteristic of reproduction output, and FIG. 6B is a diagram showing another example of a recording density characteristic of noise.

[Explanation of symbols]

 1 Polymer Substrate (Non-Magnetic Substrate) 2 First Magnetic Layer 2a Lower Layer 2b Upper Layer 3,14 Easy Magnetization Axis Direction 4 Growth Direction 5 Normal Direction 9 Cylindrical Roller 10 Evaporation Source 12 Second Magnetic Layer 13 Magnetic Film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Kawabun 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A non-magnetic substrate and Co and Cr or C formed on the non-magnetic substrate directly or via an underlayer.
a magnetic film containing a first magnetic layer containing o, Ni and Cr as main components, and a direction in which an easy axis of magnetization of the first magnetic layer is inclined with respect to a normal direction of the non-magnetic substrate. And the angle formed by the growth direction of the columnar crystal grains forming the first magnetic layer and the normal direction is smaller than the angle formed by the easy magnetization axis direction and the normal direction. Magnetic recording medium. 2. A second magnetic layer containing Co and O or Co, Ni and O as a main component is formed on the first magnetic layer, and the easy magnetization axis direction of the second magnetic layer is nonmagnetic. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is in a direction inclined with respect to a normal line direction of the substrate. 3. The angle between the easy axis of magnetization of the second magnetic layer and the normal direction of the non-magnetic substrate is smaller than the angle between the easy axis of magnetization of the first magnetic layer and the normal direction. The magnetic recording medium according to claim 2, wherein: 4. A first polymer containing Co and Cr or Co, Ni and Cr as main components on a long polymer substrate which runs along the circumferential surface of a cylindrical can, either directly or through an underlayer. When the magnetic layer is formed by the vacuum deposition method, the evaporation atom forming the first magnetic layer is 5 with respect to the normal direction of the polymer substrate.
The lower layer is formed by being incident in a direction making an angle of 0 ° or more, and then the vaporized atoms are made incident on the lower layer in a direction making an angle of 45 ° or less with respect to the normal direction to form an upper layer, and A method of manufacturing a magnetic recording medium, wherein the lower layer has a thickness of 20% or less of the layer thickness of the first magnetic layer.